The present invention has for its object to provide an endosteal implant, which is used in maxillo-dental surgery, in particular surgery of the lower maxillary bone, and including of at least one piece comprising a body to be embedded in the bone, one of the ends of which is intended to be flush with the cavity of the mouth or to be in projection in this cavity and the dimension of which, when considered in a parallel direction to its longitudinal axis, is such that this body extends through the upper cortical area, the blueberry tissue and the lower cortical area of the bone in order to bear on both of these cortical areas.
Various types of known implants are in particular subdivided into two main categories, namely a first category of implants, which is certainly the most prevalent and comprises screwed or nonscrewed cylindrical implants, strip implants, and the like, which are entered, in the case of the lower maxillary bone, through the upper cortical area of the bone and extend in the latter and the blueberry tissue, and a second category of implants which are entered, again in the case of the lower maxillary bone, through the lower cortical area of the bone and extend in the latter, in the blueberry tissue and in the upper cortical area, with a subcortical plate, possibly screwed, lining the bone and through which the implants can pass.
Those implants forming part of the first category, if they are generally well biologically tolerated by the system, present, however, various drawbacks and in particular, the major drawback, on the one hand, of causing, in the case of most of them, an important traumatism of the periodontium and the fibromucosa when they are implanted, due to the fact that the realization of the flap interrupts the blood circulation and, on the other hand, of being individually relatively not very stable, due to their relatively reduced dimensions and to their simplified bioform, when they are subjected to high mechanical stresses. To reduce the risk of mobilization of the implants of this first category, it has already been thought, instead of multiplying the number thereof above four, to stabilize them either due to a surface roughness, or by associating with them some elements bearing, on the one hand, on the implants and, on the other hand, on at least one of the vestibular or lingual cortical areas of the bone. This way of proceeding, if it is already a progress, has the drawback of not using the lower cortical areas of the bone, which are by far the most resistant.
Furthermore, these prior art first category implants also present the drawback, on the one hand, of necessitating two distinct surgical interventions which are three to six months apart, the first intervention leaving the inactive implants in an embedded condition (in "nursing") and, on the other hand, of involving many manipulations using complex equipment.
Concerning the known implants of the above-mentioned second category, if they permit a surgeon to substantially improve the mechanical stability of the implant by using the lower cortical area, more particularly due to the presence of the subcortical plate, first present some drawbacks in the surgical intervention for fitting the implants, the subcortical plate and numerous screws necessary to fix in position this plate in relation with the bone. As a matter of fact, this intervention is relatively long, it presents unquestionable operative risks and can leave relatively important visible operative traces. Moreover, the plates and implants of this kind being generally made of gold alloy, their high cost which increases the drawbacks of the surgical intervention considerably limit their extensive diffusion, the latter being moreover reduced due to the relatively small number of practitioners able to carry out such interventions. In case of post-operative problems, this second category of implants makes very delicate the removal of the implants and of the subcortical plate cooperating with the latter.
Finally, the implants of both categories very often require for fixing a prosthesis the use of an external fixing element, such as a Dolder bar, cast bridge, which is in projection with respect to the gum and which binds the various implants together.